Batteries can provide robust and dependable power storage, can be reusable, and can act as a multiplier of effectiveness for intermittent sources of in situ power generation, such as solar or wind power. Lithium-ion batteries have emerged as a leading technology due to their high energy density and low rates of self-discharge. However, the demand for batteries to possess increasingly higher power densities, fast charging times, lighter weights, and safer operation, puts a tremendous strain on the active materials that comprise the battery. This strain, often originating from the high electrical and chemical potentials that are maintained inside the device, can result in a number of different failure modes. Battery ageing can result in a slow decrease of battery performance, frequently manifested as capacity fade and increase of self-discharge rates. In other cases, battery failure can be much more acute and violent, and constitutes a significant fire and safety hazard. These catastrophic failures can result from some physical trauma inflicted upon the battery, or can happen as a result of typical use and may present little or no warning signs before failure.
New generations of lithium-ion batteries that can offer increased capacity and other performance metrics without compromising safety or reliability are required. Research into the mechanism of typical battery usage and how those mechanisms evolve in time may lead to those new generations. Methods which have been used to characterize the physical and chemical properties of lithium ion batteries and subsystems include electrochemical impedance spectroscopy (EIS); scanning probe microscopy (SPM); X-ray absorption spectroscopies such as X-ray absorption near-edge structure (XANES), X-ray absorption fine-structure (EXAFS) and X-ray tomography; electron microscopies and spectroscopies such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS); and nuclear magnetic resonance (NMR).